Heterologous Expression of HBsAg in Saccharomyces Cerevisiae

Abstract:

Hepatitis B surface antigen(HBsAg) is a major component of the hepatitis B vaccine. In the present work，we achieved its high efficient heterologous expression in the recombinant Saccharomyces cerevisiae by optimization at three levels:transcription，translation and post-translation. Compared with the constitutive promoters TEF1，TDH3，HXT7 and ADH1，the inducible promoter GAL1 substantially increased the expression of HBsAg. Moreover，compared with GCCACC and AAAAAA，the kozak sequence TACACA is more beneficial to the translation and active expression of HBsAg. More importantly，co-expression of protein disulfide isomerase(PDI) also significantly increased the expression of HBsAg. Through three levels of optimizations，the activity of recombinant HBsAg was increased from 8.87 IU/g CDW to 151.08 IU/g CDW. Finally，applying the Ni column affinity chromatography，we successfully obtained the purified HBsAg with an activity of 3.32 IU/mL.